The Collaborative International Dictionary of English v.0.48:
Maniacal \Ma*ni"a*cal\, a. Affected with, or characterized by, madness; maniac. -- Ma*ni"a*cal*ly, adv. [1913 Webster]WordNet (r) 3.0 (2006):
maniacally adv 1: in a maniacal manner or to a maniacal degree; "he was maniacally obsessed with jealousy"